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path: root/fs/xfs/libxfs/xfs_ag_resv.c
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* xfs: remove unneeded parameter from XFS_TEST_ERRORDarrick J. Wong2017-06-271-2/+1
| | | | | | | | | Since we moved the injected error frequency controls to the mountpoint, we can get rid of the last argument to XFS_TEST_ERROR. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
* xfs: use per-AG reservations for the finobtChristoph Hellwig2017-01-251-6/+41
| | | | | | | | | | | | | | | | | | | | | | | Currently we try to rely on the global reserved block pool for block allocations for the free inode btree, but I have customer reports (fairly complex workload, need to find an easier reproducer) where that is not enough as the AG where we free an inode that requires a new finobt block is entirely full. This causes us to cancel a dirty transaction and thus a file system shutdown. I think the right way to guard against this is to treat the finot the same way as the refcount btree and have a per-AG reservations for the possible worst case size of it, and the patch below implements that. Note that this could increase mount times with large finobt trees. In an ideal world we would have added a field for the number of finobt fields to the AGI, similar to what we did for the refcount blocks. We should do add it next time we rev the AGI or AGF format by adding new fields. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
* xfs: only update mount/resv fields on success in __xfs_ag_resv_initChristoph Hellwig2017-01-251-9/+14
| | | | | | | | | | Try to reserve the blocks first and only then update the fields in or hanging off the mount structure. This way we can call __xfs_ag_resv_init again after a previous failure. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
* xfs: use the actual AG length when reserving blocksDarrick J. Wong2017-01-031-0/+3
| | | | | | | | | | We need to use the actual AG length when making per-AG reservations, since we could otherwise end up reserving more blocks out of the last AG than there are actual blocks. Complained-about-by: Brian Foster <bfoster@redhat.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: simulate per-AG reservations being critically lowDarrick J. Wong2016-10-051-1/+3
| | | | | | | | | | Create an error injection point that enables us to simulate being critically low on per-AG block reservations. This should enable us to simulate this specific ENOSPC condition so that we can test falling back to a regular file copy. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* xfs: preallocate blocks for worst-case btree expansionDarrick J. Wong2016-10-051-0/+11
| | | | | | | | | | | | | | | | | | | | | | | | | To gracefully handle the situation where a CoW operation turns a single refcount extent into a lot of tiny ones and then run out of space when a tree split has to happen, use the per-AG reserved block pool to pre-allocate all the space we'll ever need for a maximal btree. For a 4K block size, this only costs an overhead of 0.3% of available disk space. When reflink is enabled, we have an unfortunate problem with rmap -- since we can share a block billions of times, this means that the reverse mapping btree can expand basically infinitely. When an AG is so full that there are no free blocks with which to expand the rmapbt, the filesystem will shut down hard. This is rather annoying to the user, so use the AG reservation code to reserve a "reasonable" amount of space for rmap. We'll prevent reflinks and CoW operations if we think we're getting close to exhausting an AG's free space rather than shutting down, but this permanent reservation should be enough for "most" users. Hopefully. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> [hch@lst.de: ensure that we invalidate the freed btree buffer] Signed-off-by: Christoph Hellwig <hch@lst.de>
* xfs: set up per-AG free space reservationsDarrick J. Wong2016-09-191-0/+325
One unfortunate quirk of the reference count and reverse mapping btrees -- they can expand in size when blocks are written to *other* allocation groups if, say, one large extent becomes a lot of tiny extents. Since we don't want to start throwing errors in the middle of CoWing, we need to reserve some blocks to handle future expansion. The transaction block reservation counters aren't sufficient here because we have to have a reserve of blocks in every AG, not just somewhere in the filesystem. Therefore, create two per-AG block reservation pools. One feeds the AGFL so that rmapbt expansion always succeeds, and the other feeds all other metadata so that refcountbt expansion never fails. Use the count of how many reserved blocks we need to have on hand to create a virtual reservation in the AG. Through selective clamping of the maximum length of allocation requests and of the length of the longest free extent, we can make it look like there's less free space in the AG unless the reservation owner is asking for blocks. In other words, play some accounting tricks in-core to make sure that we always have blocks available. On the plus side, there's nothing to clean up if we crash, which is contrast to the strategy that the rough draft used (actually removing extents from the freespace btrees). Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
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